Odd brass length after fire form'n

[wildchild]

While fireform'n some dasher brass with the new bluebox stuff I noticed my brass length was runn'n from 1.510 to 1.545. I never did measure before fire'n to see if it was short before hand so maybe it was, but doubt it. Any one else notice this issue?
Also this didnt happ'n with the other 100 rds I did with the hard jam in the lands, this happened on a batch of 50 I necked up to creat false shoulder (just thought id try this theory) then back down and had some jam with the bullets. ??? ???

 

[Skeeter]

I fire formed about 650 Dasher cases using various methods over the years. COW, sized .257 then back to .243 to create a bump to head space off and just plain old 6BR loaded and fired. All of them worked. The COW was the fastest, least expensive method and I did about 350 rounds in my basement. Only thing you had to keep an eye on was cleaning the chamber every 30 rounds so carbon would not build up. The false shoulder method worked great and I got to kill PD's while fire forming. The standard 6mmBR rounds loaded and fired also worked well as my rifle is a falling block and really didn't need the false shoulder as their was no bolt to move upon firing.

In every method, the cases were slightly shorter after fire forming. However, after an actual full dasher load with the preformed case they stretched out to full size. I also used an inside neck turner to remove the doughnut area that forms in the SNJ from fire forming the cases.

One last observation... if you don't clean the chamber every 25-30 rounds carbon will build up and cause irregular case mouths and lengths. If this happens, trim to even out and next firing will full size the cases and clean the chamber often.

Last thing, for the COW method I had a surrogate barrel just for fire forming.

Skeeter

 

[shooter63]

i have noticed the same thing wildchild ithink its some difference in brass even in twice fired brass i notice different amounts of resestence in press handle setting sholders back also it seems to me that it looks more annealed than older lots almost rust looking color could be my eyes but not my feelof the press handle just my observations . but when all is said &done lapau is still # 1 shooter63= +.

 

[bozo699]

Skeeter,
I am building a couple of brx's do you think I will have this carbon problem fire forming them? I know how to get the carbon out of the throat but how do you get it out of the chamber? What is your method? Thanks
Wayne.

 

[johara1]

Remove all traces of lube from the chamber and brass,they will be longer. as the gun heats up they get shorter. You can make them longer by adjusting the load.
This is why the new brass is hurting the dasher, the blow lengths are harder to reach......jim